1. Technical Field of the Invention
The present invention relates generally to sealing devices to prevent product from leaking from contained area and, in particular, to a sealing device for sealing the inside of a container through a radial expansion caused by a user-applied force to the top of the seal.
2. Description of Related Art
Liquids need to be sealed in containers especially during transport to avoid spillage of the contents. Numerous methods to seal containers can be found in prior art. Many attempts have used a downward, axial force to radially exert a force in a manner meant to seal. For example, one prior art reference relates to a garbage can lid. A cross section of the lid is shown in FIG. 1. The lid operates as follows: At the end of each rod, an elastic, roughly U-shaped latch joins the distal end of the rod with the bottom of the lid roof. The annular rim of the garbage can fits snugly between the concaved U-shaped latch and the skirt wall comprising the outer diameter of the lid. When an axial force is applied on the rods in the center of the lid by pulling the handle up (away from the lid), the rods act to pull the U-shaped latches inward, increasing the space between the U-shaped latch and the outer diameter of the skirt wall. This allows the lid to be freely removed. This design, however, has its drawbacks. For example, the container can only be sealed with a lid manufactured to fit one container diameter. In other words, the diameter of the lid must fit the diameter of the can. Secondly, there is no way to seal without using a lid. For example, if one wants to transport two different fluids without mixing them, then two separate containers must purchased, loaded, shipped, unloaded and eventually discarded.
Another apparatus for sealing a fluid in a container is illustrated in FIG. 2. Here, an elastic O-Ring is attached around a frame. Attached to the top of the frame is an expandable metal snap ring. As the cam mounted in the center of the disc is rotated, the snap ring expands radially outward to fit into a circumferential groove cut into the container to be sealed. This design also has limitations. For example, a groove must be machined in the inside diameter of the container to be sealed. Furthermore, the outside diameter of the frame, and in particular the outside diameter of the elastic O-Ring must be relatively similar to the inside diameter of the area sought to be sealed.
One prior art example of a force or pressure causing a seal is illustrated in FIG. 3. When the vessel is pressurized, a pressure difference acts on the diaphragm to press an annular plate driven by the diaphragm against the O-ring while the cover is secured by a bayonet. However, absent a pressure in the vessel there is no seal. Furthermore, multiple fluids cannot be kept separate in the same container. Moreover, the lid must be tailor made to fit the container.
Consequently, a need exists for a device that can be used to seal containers with a range of inside diameters. Furthermore, a need exists for a seal that can be placed in various axial positions within a container without modifying the container.